1. Technical Field
The present invention relates to a gluing method and device for applying glue to a corrugated board sheet in a gluing process in a box-producing apparatus which produces a box of a corrugated board sheet manufactured by a corrugator, in which a gluing defect of a gluing area is eliminated and the glue is firmly applied to the gluing area.
2. Background Art
A corrugated board sheet manufactured by a corrugator is processed for printing, making creasing lines and slotting on a conveyance line of the box-producing machine, and then formed into a square tube in a gluing step and a folding step in which a gluing margin of one panel of four-panel box is overlapped and glued to a join flap of the opposite panel so as to form a body in a shape of a square tube, and flaps extending from each panel form a bottom part and a top part of the box.
FIG. 5 illustrates a general structure of a box production line of the corrugated board box. In FIG. 5, the box production line starts from the right-hand side and the corrugated board sheet S is conveyed in a direction of arrow a so as to conduct the box-producing process. On the upstream side of the box-producing process, front and back linerboards and a corrugated board sheet S of a corrugating medium to be interposed between the linerboards, are produced and stacked in a paper supply part A. The corrugated board sheet S shown in FIG. 5 has already been cut into predetermined sizes in width and length directions in the corrugator line and a creasing line b is made in a length direction thereof.
In the paper supply part A, the corrugated board sheets S are positioned in the same direction and stacked so as to form a group G1 of the corrugated board boxes. The corrugated board sheet S of the bottom of the supply part is fed individually from the supply part A to a flexo-printing machine B in which four colors in total (at least two ink colors) are printed on the corrugated board sheet S one color at a time, and the printed corrugated board sheet S is transferred to a slotter•creaser C which performs the steps of making creasing lines and slotting in a plurality of places on the corrugated board sheet S in a traveling direction (four places in FIG. 5) so as to form creasing lines c and slots d parallel to the short end of the sheet S and a gluing margin f.
Subsequently, a hole-making step is performed by a die-cut unit D, and the gluing margin f is applied glue and folded in a folding unit D so as to attach the gluing margin f to the panel e, thereby forming a square-tube shaped corrugated board box W. Next, the corrugated board box W in a flat state is transferred to a counter ejector F in which the number of sheets is counted and stacked in the same direction so as to make a group G2 of the corrugated board boxes. Finally, the corrugated board box group G2 is transferred to a binding machine located in a downstream side of the counter ejector F in the transferring direction by a transferring conveyor so as to bundle the corrugated board boxes ready for shipment.
In FIG. 5, a gluing device 010 for applying glue to the gluing margin f of the corrugated board sheet S is arranged in an immediate downstream side of the die-cut unit D. A conventional gluing device 010 is illustrated in FIG. 6, in which the corrugated board sheet S is fed into a pair of guide bars 011 so as to space out the cut cardboard sheets S for the gluing step. The guide bar 011 has a glue gun 012 at an end thereof. Glue g is supplied to the glue gun 012 and a plurality of nozzles not shown in the drawing are arranged at a tip thereof. In an upstream side of the glue gun 012, a glue-timing sensor 013 is provided.
The glue gun 012 houses a solenoid valve and is constructed such that, the glue is ejected from the glue gun by sending electricity to the solenoid valve. When the corrugated board sheet S passes the glue-timing sensor 013, the glue-timing sensor 013 detects the passing of the corrugated board sheet S and the solenoid valve of the glue gun operates in accordance with the gluing timing at which the corrugated board sheet S passes the glue gun 012 and plural lines of glue g are applied on the gluing margin f from the nozzles.
Patent Document 1 discloses a gluing device which can directly detect the gluing margin without causing a malfunction of the detection device detecting the front and rear ends of the corrugated board sheet so that the glue setting can be easily changed in a short period of time depending on an order change of the corrugated board sheet. As a result, the productivity of a box manufacturing machine can be improved.